Consumer Redressal

On 25/03/2013, I bought a Sony Vaio Laptop (SVE 1513 ACNB/IN5), with 3 yrs warranty (1yr. + 2yrs.). Within 7 months the LCD got cracked for an unknown reason. When I have noticed the crack, before that neither I was carrying the Laptop nor it was in use. When I visited Sony Service Centre, they forcefully put the problem under physical damage condition and told me that I have to pay Rs. 9138/- to change the LCD. There is no evidence of physical damage on the laptop and even I am not sure whether that was a manufacturing defect or not. After replacing if the LCD gets cracked again then again I have to pay to change this if it is under warranty then also, is it the warranty policy? Could you please tell me why should not my laptop be replaced, when there is no fault of mine except choosing the Sony Vaio brand for me? Being a jobless person, it has become a mental and financial burden for me now and has hampered my Job exam preparation also. Kindly look into the matter at your earliest.